1. Field of the Invention
This invention relates to a liquid crystal display device and, more particularly, to a liquid crystal display device with a black film which is implemented in such a manner that a liquid crystal display device reduces bright lines, light leakage and line cloak and also to a method of fabricating the same.
2. Description of the Prior Art
Recently, a liquid crystal display device has desirable features, such as a light and slim body, a low power drive, and so on. Also, the liquid crystal display device has a greatly enhanced picture quality due to improvement of the liquid crystal material and development of the processing technique of the fine pixel (or picture element). The application of the liquid crystal display device is gradually extended to devices other than computers. The liquid crystal display device is composed of a liquid crystal panel and a driving circuit for driving the liquid crystal panel. The liquid crystal panel generally includes liquid crystal cells arranged between two glass substrates (i.e., a upper glass substrate and a lower glass substrate) in the matrix formation and switching elements, such as a TFT (thin film transistors) array, for switching each of the signals supplied to the liquid crystal cells. In order to drive the liquid crystal panel, the driving circuit applies a control signal, a video signal and so on to the liquid crystal panel.
Referring to FIG. 1, a prior liquid crystal display device consists of a liquid crystal display module for displaying a picture corresponding to the video signal. The liquid crystal display module includes a sheet material 10 for directing a light beam from a back-light guide 12 in the vertical direction, a lower polarizing plate 8 for polarizing the light beam through the sheet material 10, a lower glass substrate 6 fabricated with switch elements, an upper glass substrate 4 disposed on the lower glass substrate 6 to form a liquid crystal layer, and an upper polarizing plate 2 for polarizing the lights from the upper glass substrate 4.
In the liquid crystal display module, the switch elements of the liquid crystal panel are driven according to the control and video signals from drive integrated circuits connected with a PCB (printed circuit board) to vary the arranged state of the liquid crystal. The amount of light passing through the liquid crystal panel is controlled on the basis of the arranged state of the liquid crystal so that the picture corresponding to the video signal is displayed. On the other hand, the back-light unit, used as a light source of the liquid crystal display module, consists of a lamp 20, a lamp housing 22, a light guide 12 and a reflective sheet 14. The light beam generated in the lamp 20 proceeds toward the light guide 12, and the light beam is guided to the liquid crystal display module by the light guide 12. The lamp housing 22 surrounds the lamp 20 to reflect the light beam generated in the lamp 20 to the light guide 12. The reflective sheet 14 installed on the lower and side surfaces of the light guide 12 also reflects the lights from the lower and side surfaces of the light guide 12 to the liquid crystal display module.
The liquid crystal panel is divided into a display area 27 and a non-display area 25, as shown in FIGS. 2A–2C. The display area 27 substantially transmits the light to display the picture. The picture is not displayed in the non-display area 25. A black matrix 26 is created on the part of the non-display area 25. Since the lower glass substrate 6 of the liquid crystal panel is formed larger than the upper glass substrate 4, light leakage, bright lines, line cloak and other undesirable characteristics appear on the remaining portion which the black matrix 26 does not cover. Light leakage and bright lines are caused by light leaking out from the back-light unit in the remaining portion. Line cloak is generated by covering the line in accordance with a visual angle.
In order to prevent bright lines, light leakage and line cloak, a protective sheet 10a is provided on the liquid crystal panel. In particular, the sheet material 10 is provided with a diffusion sheet 10c for diffusing the light guided by the back-light unit, a prism sheet 10b for concentrating the light diffused by the diffusion sheet 10c to each of the liquid crystal cells on the liquid crystal panel, and the protective sheet 10a for protecting the prism sheet 10b. These diffusion, prism and protective sheets 10a through 10c are sequentially disposed on the back-light unit to transmit the light from the back-light unit to the liquid crystal panel. The protective sheet 10c is fabricated larger than the liquid crystal panel to prevent bright lines, light leakage and line cloak on the liquid crystal display device.
A silicone pad 18 is attached on one end of the protective sheet 10c, such as, on the right edge of the protective sheet 10c. Also, a black pattern 24 is printed on the other end of the protective sheet 10c, i.e., on the left edge of the protective sheet 10c. In detail, the silicone pad 18 attached on one end of the protective sheet 10c, as shown in FIG. 1, prevents bright lines, light leakage and line cloak. The black pattern 24 printed on the other end of the protective sheet 10c also prevents bright lines, light leakage and line cloak. Furthermore, the silicon pad 18 is positioned on the rest of the non-display area 25, and the black pattern 24 is installed to overlay with the black matrix 26. However, the protective sheet 10c is crumpled by pressure caused when the silicone pad 18 is attached on its one end. To this end, a crumple appears on the screen and the liquid crystal display device has a lower quality. The liquid crystal display device also is decreased in the manufacturing process. Since the protective sheet 10c must be fabricated larger than the liquid crystal panel, one end of the protective sheet 10c is installed adjacent to the lamp 20. To this end, the protective sheet 10c is crumpled by heat generated in the lamp and a crumple appears on the screen. As a result, the quality of the liquid crystal display device is reduced. Also, the liquid crystal display device has a lower manufacturing yield rate because of the difficulty in assembling of back-light unit.